Emily Blunt (left) and Charlize Theron star as good and evil queens in The Huntsman: Winter's War.

Given that English rose Emily Blunt first sashayed onto our screens as the haughty Emily Charlton in 2006’s The Devil Wears Prada, you could be forgiven for having trouble reconciling the same star with her recent roles in all-action thrillers and murder mysteries. Although there was little hint of it at the time, behind her character’s clipped tones and passion for fashion lay an actress made of much sterner stuff.

Last year, Blunt triumphed in the lead role as female federal agent Kate Macer in Denis Villeneuve’sSicario, winning acclaim from critics and fans alike. Her next role is as part of Tate Taylor’s The Girl on the Train – where the London-born 33-year-old will be playing the deeply flawed alcoholic divorcee, Rachel Watson.

“Rachel is a messy, broken character whose alcoholism has ruined her life,” Blunt says. “Although the book and the film have a thriller element to them, I was more fascinated with how the story explores alcoholism, addiction, voyeurism and the life of this damaged woman. I think a lot of people are going to relate to those themes.”

For Blunt, the chance to take on a darker role like this signals a new, more mature side to the undeniably talented actress.

“I now know that I’m capable of taking on roles that I would never have imagined doing before,” she agrees. “I don’t know if I would have been ready to play Rachel several years ago.”

The turning point for Blunt came in the “strength and determination” she found in becoming a first time mother to daughter Hazel in 2014 with her husband of six years, and fellow actor, John Krasinski. Her star turn in Sicario came a year later, giving Blunt the perfect platform to showcase her newfound desire to branch out artistically. “Sicario was one of the most interesting and demanding experiences I’ve ever had on film,” she says. “It was a dream role for me to play such a terrific woman who was strong enough to hold her own with the guys, and could be feminine and vulnerable too.”

Sicario was one of the most interesting and demanding experiences I’ve ever had on film

Emily Blunt

Having reinvented herself as a woman not to be messed with, Blunt is determined to maintain the momentum of Sicario’s success in order to promote the need for stronger female roles across Hollywood.

“There are too many films geared to teenage boys,” she explains. “It’s great that we have been seeing many more films centred on female characters that have been successful, and prove that women’s stories can be just as interesting, and can also find an audience.

“I’ve been avoiding films where the women are simply there to support the male character and don’t really move the story forward. We need more stories that present women as serious, complicated characters who can be both determined and vulnerable.”

Blunt credits her experience of motherhood with giving her the confidence to stand up for herself in the patriarchal world of cinema.

“I’m more focused now; being a mother has made me more emotionally aware and intense,” she nods. “In the past, I was worried all the time about my work.”

Having said that, Blunt’s ever-expanding family – her second daughter, Violet, was born earlier this year – has meant that the actress is determined to be more selective with the projects she undertakes.

“I don’t want to be away from my family for long periods of time unless I’m very committed to a particular project,” she explains. “I love my job so much that I want every film to mean something and for that time on the set to really count.”

Her upcoming work, however, suggests there’s still a less serious side to the star of Sicario and The Girl on the Train. As well as lending her vocal talents to two animated comedies, Animal Crackers and My Little Pony: The Movie – a welcome, family-oriented break from the action-packed adventures that have defined her recent career – Blunt is set to star as the iconic lead in Disney’s proposed sequel to 1964’s Mary Poppins, set for release in 2018.

And despite recently telling TIME that the chance to emulate fellow beloved Brit Julie Andrews was the “greatest gift” she had received in her career so far, Blunt is pragmatic. “I’ve learnt that it’s hard to know how a film will turn out, even though you’ve read the script and you think it’s going to be great,” she says. “There’s a lot of faith involved in choosing a film, and each film is a risk. You’ve just got to rely on your instincts and pick a project you love.”

Riding a wave of critical praise, including several nominations and a Golden Globe win, expectations are definitely high for Blunt’s upcoming turn as everybody’s favourite magical matriarch. What is clear, however, is that no matter what the challenge, superwoman Blunt is ready to meet it head on.

Emily Blunt’s road to success

1983 Born in Wandsworth, London2005 Wins a Golden Globe for her work in BBC drama Gideon’s Daughter2007 Nominated for Best Actress in a Supporting Role BAFTA for her work in 2006’s The Devil Wears Prada2010 Marries star of the US Office, John Krasinski2011 Takes on her first role in a thriller alongside Matt Damon in The Adjustment Bureau2015 Becomes a naturalised US citizen2018 Will reprise fellow iconic British actress Julie Andrews’ lead role in the long-awaited Mary Poppins sequel